Electrophotographic copying machine

ABSTRACT

AN ELECTROPHOTOGRAPHIC COPYING MACHINE OF THE TYPE IN WHICH BOTH OF AN ORIGINAL TO BE REPRODUCED AND A COPY PAPER ARE MOVED IN SYNCHRONISM WITH EACH OTHER RELATIVE TO A SLIT EXPOSURE OPTICAL SYSTEM WHEREIN THE COPY PAPER, UPON ADMISSION INTO A CHARGING STATION, ACTUATES A COMNON SWITCH WHICH ENERGIZES THE CHARGER, THE LIGHT SOURCE IN THE EXPOSURE OPTICAL SYSTEM AND AN ELECTROMAGNETIC CLUTCH FOR COUPLING AN ORIGINAL CARRIER DEVICE TO A DRIVE MECHANISM UNTIL THE COPY PAPER PASSES THROUGH THE EXPOSURE STATION. UPON DISCHARGE OF THE COPY PAPER FROM THE EXPOSURE STATION, THE CHARGER, LIGHT SOURCE AND CLUTCH ARE DE-ENERGIZED WHILE A REVERSE CLUTCH IS ENERGIZED SO AS TO RETURN THE CARRIER TO THE INITIAL POSITION. IN ORDER TO ATTAIN THE PRECISE REGISTRATION OF THE LEADING EDGES OF THE COPY PAPER AND ORIGINAL, A DEVICE FOR DRIVING THE CARRIER AFTER PREDETERMINED TIME DELAY WHEN SAID ELECTROMAGNETIC CLUTCH IS ENERGIZED IS PROVIDED ALONG WITH A MEMBER FOR LOCKING THE CARRIER IN THE INITIAL POSITION UNTIL A START BUTTOM IS DEPRESSED, AND A MECHANISM FOR PREVENTING ANY SLIPPAGE OF THE CARRIER DRIVE CABLE.

June 27, 1972 5 u suzum E'IAL 3,672,762

ELECTROPHOTOGRAPHIC COPYING MACHINE Filed April 24, 1970 2 Sheets-Sheet 1 INVENTORS SHIGERU SUZUKI KELJI SUGITA YASUMORI NAGAHARA ATTORNEY June 27, 1972 SHIGERU SUZUKI ErAL 3,672,762

ELECTROPHOTOGRAPHIC COPYING MACHINE Filed April 24, 1970 2 Sheets-Sheet 2 7 r INVENTORS .SHIGERU SUZUKI KEIJI SUGITA YASUMORI NAGAHARA ATTORNEY United States Patent US. Cl. 355- 7 Claims I ABSTRACT OF THE DISCLOSURE An electrophotographic.copying machine of the type in whichboth of an original to be reproduced and a copy paper are moved in synchronism with each other relative to a slit exposure optical system wherein the copy paper, upon admission into a charging station, actuates a common switch which energizes the charger, thelight source in the exposure optical system and an electromagnetic clutch for coupling an original carrier device to a drive mechanism until the copy paper passes through the ex} posure station Upon discharge of the copy paper from the exposure station, the charger, light source and clutch are de-energized while a reverse clutch is energized so as to return the carrier to the initial position. In order to attain the precise registrationof the leading edges of the copy paper and original, a device for driving the carrier after predetermined time delay when said electromagnetic clutch is energized is provided along with a member for locking the carrier in the initial position until a start button is depressed, and a mechanism for preventing any slippage of the carrier drive cable.

BACKGROUND OF THE INVENTION original carrier over the guide rails. Furthermore, when the original is not firmly placed upon the original holder in predetermined position, the precise registration is not attained.

An electrophotographic copying machine of the type described generally includes a copy paper feeding station, a charging station, an exposure station, a developing station, a fixing station and an original carrier. It is not necessary to drive all of them all the time but they are preferably driven intermittently in a predetermined timescheduled relation with each other. Therefore many electrical switches are used to provide a time-schedule control system in the electrophotographic copying machines in the prior art. An increased number of structural parts presents some problems in the assembly, adjustment, maintenance, and repairs of such electrophotographic copying machines.

The present invention overcomes those related problems encountered in photocopying machines in the prior art and of the type described.

Accordingly it is the general object of the present invention to provide an improved electrophotographic copying machine of the type in which both an original to be reproduced and a copy paper are moved in synchronism with each other and relative to a slit exposure optical system.

It is one of the objects of the present invention to provide an electrophotographic copying machine of the character described above in which almost all of the various stations and other mechanisms are intermittently driven or energized in precise synchronism with each other in accordance with a predetermined time schedule by a common switch, thereby reducing the required number of structural parts while increasing reliability and dependability in operation.

- *It isanother object of the present invention to provide an electrophotographic copying machine of the character described above having a time delay control means which is adjustable so as to permit the precise registration of the optical registration of the leading edges of the original to be reproduced and a copy paper upon admission of the latter in the exposure station without the use of any device upon which the original is placed to be reproduced is displaced in precise synchronism with the movement of the copy paper through at least an exposure station, so that the whole pattern uponthe original may be copied upon the copy paper. In machines of this type, it is exceedingly difiicult to attain the precise registration of the 1 leading edges of the originaland copy paper in'the exposure station since they are registered optically not physically. For this purpose, the conventional photocopy ing machine of'the'type describedvincorporates a micro switch or the like in the exposure station so that when p the leading edge of the copy paper actuates the switch,

the original carrier may be started immediately in synchronism with the movement of the copy paper through .the exposure station. Therefore some complexity of the structure of the photocopying machine is inevitable, re-

carrier is not smoothly displaced in synchronism with the movement of the copy .paper throughout its passage through the exposure station, the electrostatic latent image formed upon thecopy paper will becomedeformed. This defect is caused generally by the slippage. of the carrier drive wire or the like and by unsmooth movementof the special switch, thereby facilitating to a degree the assembly 'and adjustment of the copying machine.

It is a further object of the present invention to provide an electrophotographic copying machine of the character described above having an original carrier which may be securely locked in initial or home position so as to facilitate the placement of an original thereover and which has drive belting causing no slippage thereof, thereby further enhancing the precise registration of the original and the copy paper.

f It is a-further object of the present invention to provide an electrophotographic copying machine of the character described above which is compact in size and improved in appearance.

It is a still further object of the present invention to provide amethod for retaining in a most simple yet very positive manner the ball bearings of the guides for th original carrier. Y

SUMMARY OF THE INVENTION To attain the above and other objects, the present invention provides an electrophotographic copying machine of the type in which both an original to be reproduced and a photosensitized copy paper are moved for exposure relative to a slit exposure optical system including a light source and in synchronism with each other characterized by the combination comprising: means at a feeding station for feeding the copy papers one by one; means at a charging station for imparting a charge layer to the surface of the copy paper, an exposure station at which a light image of the pattern of the original is projected upon the charged copy paper by said slit exposure optical system, thereby forming an electrostatic latent image thereon, means at a developing station for developing said electrostatic latent image into a visible image; means at a fixing station for fixing said develped image, a drive mechanism including means for driving said copy paper feeding station: means for transporting the copy paper from said copy paper feeding station through said charging station, said exposure station, said developing station and said fixing station: and means for driving an original carrier upon a pair of spaced guide means relative to the slit exposure optical system and in synchronism with the passage of the copy through aid exposure station. The original carrier driving means includes reverse clutch means for returning said original carrier back to its initial position upon completion of the exposure stroke; and switch means actuable by the copy paper being transported to be selectively switched between two positions, said switch means in one of said two positions energizing simultaneously said charging station, said light source in said slit exposure optical system and clutch means for coupling said drive mechanism to said carrier drive means, and in the other of said two positions de-energizing said charging station, said light source and said clutch means while energizing said reverse clutch means so as to reverse the coupling of said carrier drive means to said drive mechanism, thereby returning said original carrier back to its inital position. Means for locking said original carrier in said initial position are provided and adapted to be actuated in response to the depression of a start button of said copying machine so as to be released from the locking position, and time-delay control means are included for driving said original carrier drive means in a predetermined time delay after said clutch means is energized by said switch means for attainment of the precise registration of the leading edges of the original and copy paper upon admission of the latter into said exposure station.

According to one embodiment of the present invention, the time delay control means comprises a pair of driven pins extending from one side wall of a drive pulley for driving the original carrier and a drive pin extending from a rotary shaft loosely carrying the drive pulley. The pair of driven pins are diagonally spaced apart from each other and the drive pin engages with either of the driven pins so as to rotate the drive pulley in the forward or exposure direction or in the reverse direction. The drive pin is normally in engagement with the driven pin for the reverse rotation so that upon rotation of the rotary shaft in the forward direction, the drive pin makes an idle run from the driven pin for the reverse rotation to the driven pin for the forward rotation and then engages with the latter so as to drive the pulley in the forward direction. Thus the time delay control is effected. Furthermore since at least one of the driven pins is adjustable in position, a suitable time daley may be provided as needs demand.

In one embodiment of the present invention, the switch means comprises a seesaw type switch which is closed when the copy paper enters into the charging station and is opened when the copy paper is completely discharged out of the exposure station.

The above and other objects, features and advantages I of the present invention will become more apparent from the following description of the preferred embodiment thereof taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 3 is a fragmentary view illustrating a ball and its retainer in the suporting means of FIG. 2;

FIG. 4 is a diagrammatic view for explanation of the relative position between the ball and retainer of FIG. 3;

FIG. 5 is a fragmentary view of the retainer;

FIG. 6 is a perspective view of a drive pulley for an original holder;

FIG. 7 is a fragmentary sectional view of part of the drive pulley of FIG. 6;

FIG. 8 is a top view partly in section of braking means for the drive pulley of FIG. 6;

FIG. 9 is a side view of the braking means of FIG. 8;

FIG. 10 is a diagrammatic front view illustrating a copy paper feed mechanism;

FIG. 11 is a sectional view of the copying machine shown in FIG. 1; and

FIG. 12 is a diagrammatic view for explanation of a drive mechanism of the copying machine of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 illustrating one preferred embodiment of the present invention, reference numeral 1 designates a main body of an electrophotographic-copying machine; 2, a transparent holder for an original to be copied; 201, an original holder frame or original carrier; 3, a pair of guide rails laid upon the front and rear walls 1a of the main body 1 for slidably supporting the original holder frame 2a; 4, a cartridge containing copy papers; 5, a front cover for the main body 1; 6, a control panel upon the front cover 5; 6a, a main switch button; 6b, a pilot lamp; 60, a print-start button; 6d, an exposure adjustment sliding button; 7, a rear cover; and 8, an outlet through which the copies are discharged from the machine. Within the main body 1 are housed a charging device, an exposure device, a developing device, a fixing device and a drive mechanism to be described hereinafter. Both the original holder or carrier 2 and a copy paper are moved for exposure of the copy paper relative to an exposure optical system and in synchronism with each other.

As shown in FIG. '2, longitudinal V-grooves 3a are formed in both the upper and lower surfaces of the rails 3. A plurality of balls 10 rotatably supported by a U-shaped retainer 9 are fitted into the V-shaped grooves 3a between the rails 3 and the frame 2a. As shown in FIG. 5, the retainer 9 is provided with ball receiving holes having a pair of inwardly extending lugs 9a and 9b which are bent in the opposed directions relative to each other. The ball 10 is fitted into the hole and held by the pair of lugs 9a and 9b and the peripheral edge of the hole for rotation, as best shown in FIG. 3. Even when a force acting in the direction indicated by the arrow a in FIG. 4 acts upon the ball 10, the diameter d of the ball 10 is larger than the distance D between the lug 9b and the peripheral edge 90 so that the ball 10 is positively prevented from falling out of the ball retaining hole of the retainer 9. Thus, it is readily seen that the orignal holder frame 2a rides smoothly upon the rails 3.

I The arrangement of various devices housed in the main body 1 are best shown in FIG. 11. The copy paper cartridge 4 is supported at its rear portion by a supporting member 11 whose stay 11a is firmly anchored to the bottom of the main body 1 by a stay retaining member 11b. A copy paper guide plate 12 is firmly fixed to the front and rear walls 1a of the main body 1 and an upright supporting pin 13 is fixed to the horizontal portion of the guide plate 12 so as to engage with a copy paper supporting plate 4a in the cartridge 4. The stack of copy papers upon thesupporting plate 411 in the cartridge 4 is held in position by means of retaining pawls 4b formed at the upper cornersof the inner surface of the front (leading) wall of the cartridge 4. When the cartridge 4 is set in position upon the supporting member 11 and the pin 13 as shownin FIG. 11, the front portion of the outer casing of the cartridge 4 lowers by its own weight and the stack of copy papers 14 are held in position by the retaining pawls 4b, whereby the copy papers 14 are ready to be fed into the machine. When the cartridge 4 is set, its cover 40 is half opened as shown in FIG. 11 so that a copy paper feed roller 15 may contact the upper surface ofthe copy paper 14. The half-opened cover 40 also serves to prevent the copy papers 14 from being exposed by the external light.

As shown in FIGS. and 11, the feed roller 15 is carried by a rotary shaft 17 which is rotatably journalled in one of the arms of a pair of rocking members 16 (only one is shown). The rocking member 16 is pivotably fixed to the front or rear wall 1a by a pin 18. A cam follower roller 20 is rotatably fixed to the other arm of the rocking member 16 for engagement with a cam 19 which is carried by a rotary shaft 21 which is journalled in the front and rear walls 1a of the main body 1. The cam 19 is drivingly coupled to a drive mechanism to be described hereinafter through a clutch 22 which is controlled by a pawl-like member 24 which rocks by the movement of the plunger of an electromagnet 23. The electromagnet 23 is energized upon depression of the print-start button 60 so that the pawl-like member 24 is pivoted, thereby moving away from the clutch 22. Upon disengagement of the pawl-like member 24 from the clutch 22, the latter permits the cam 19 to make one rotation in the direction indicated by the arrow b in FIG. 11. When the cam 19 is not rotating, the cam follower roller 20 is so arranged as to engage with its larger diameter portion or most extending portion, but as the cam 19 rotates the cam follower 20 comes into contact with the smaller diameter portions, so that the feed roller 15is gradually lowered and made to contact the copy paper 14 when the cam 19 rotates to the position indicated by the chain line 19A in FIG. 10. Since the feed roller 15 is rotating in the direction indicated by the arrow c in FIG. 11 by the drive mechanism to be described hereinafter during the reproduction operation, the feed roller 15 coacts with the retaining pawls 4b so as to feed the uppermost copy paper 14 through'the guide plate 12 toward a pair of feed rollers 25 and 26 pressed against each other.

A guide member 27 is fixed to the undersurface of the rocking member 16 so as to guide the copy paper 14 fed by the feed roller 15 toward the pair of feed rollers 25 and 26 whenthe arm carrying the feed roller 15 of the rocking member 16 is lowered. It is noted that the rocking member 16 is coupled to means for controlling a number of repetitive actions of this rocking member.

The cam profile of the cam 19 is of course designed in such a manner that the feed roller 15 is firmly pressed against the copy sheet 14 during the interval from the time when the copy paper 14 is started to be fed until the time when the leading edge of the copy paper 14 is held between the pair of feed rollers 25 and 26 and that the roller 15 may be moved away from the copy paper 14 when the leading edge of the copy paper 14 is firmly held between the pair of feed rollers 25 and 26. That is, the peripheral length of the smaller diameter portion of the cam 19 for causing the above described motion of the feed roller 15 is substantially equal to the smallest size of the copy papers in the cartridge 4.

The pair of feed rollers 25 and 26 rotatably journalled between the front and rear walls 1a of the main body 1 are driven in the direction indicated by the arrow d in FIG. 11 by the drive mechanism to be described hereinafter. Downstream of the feed rollers 25 and 26 are disposed a pair of chargers 27 and 28 having needleshaped electrodes 27a and 28a respectively. Below the lower charger 28 is disposed a seesaw type switch 29 and-one arm of its rocking switch actuating element 29a is so arranged as to engage when one arm of a rocking member 30 as shown in FIG. 11. The other arm of the rocking member 30 extends into the path of the copy paper between the upper and lower chargers 27 and 28, so that when the leading edge of the copy paper 14 engages the upper arm of the rocking member 30, the actuating eelment 29a is pivotably displaced to a position 29aA indicated by the broken lines in FIG. 11, thereby closing the switch 29. Therefore, the chargers 27 and 28 are energized so as to impart a charge to the copy paper 14 in a manner well known in the art. The charged copy paper :14 is transported toward an exposure station 33' by a pair of feed rollers 31 and 32 so that when the copy paper is passing between a pair of transparent guide plates 34 and 35, a light image is projected upon the copy paper 14, thereby forming a latent electrostatic image in a manner well known in the art.

A rocking member 39 similar in construction as that of the rocking member 30 described hereinabove is arranged below the exposure station 33 in such a manner that the upper arm of the rocking member 39 extends into the path of the copy paper between the exposure station 33 and a pair of feed rollers 36 and 37 which transports the exposed copy paper 14 toward a developing device or station 38. The lower arm of the rocking member 39 engages with the other arm of the actuating element 29a of the switch 29 in such a manner that when actuated by the copy paper 14 the rocking member 39 holds the actuating element 29a at the position 2911A after the trailing edge of the copy paper has passed over rocking member 30 and until the copy paper 14 has completely passed through the exposure station 33. By this arrangement switch 29 remains on so that, the charge may be imparted uniformly and positively to the Whole surface of the copying paper 14.

The two pairs of feed rollers 31 and 32; and 36 and 37 are rotatably journalled between the front and rear walls 1a of the main body 1 and are driven by the drive mechanism to be described hereinafter in such a manner that the movement or transportation of the copy paper 14 can be precisely synchronized with the movement of the original carrier 2.

The developing device 38 comprises a developing solution chamber 40 and a plurality of copy paper guide members 40a, 40b and 400 disposed Within the chamber 40 (see FIG. 11). The copy paper 14. is advanced along the guide members 40a, 40b and 400 immersed in the developing solution in the chamber 40, whereby the latent electrostatic image upon the copy paper 14 is developed into a visible image in a manner well known in the art. The developed copy paper 14 is then transported by a pair of feed rollers 41 and 42 toward a fixing device or station 43 including a pair of guide members 45 and 46 which define a space in communication with a heated air supply pipe 44 and two pairs of feed rollers 47 and 48; 49 and 50 disposed at the inlet and outlet of the fixing device or station 43 respectively. While the developed copy paper 14 passes through the space between the upper and lower guide rnmbers 45 and 46, the developed image is fixed by the heated air supplied from the pipe 44 and then the fixed copy paper 14 is discharged by the pair of feed rollers 49 and 50 through the outlet 8 out of the machine. The rollers 41, 42, 47, 48, 4'9 and 50 are journalled between the front and rear walls 111 of the main body 1 and are driven by the drive mechanism to be described hereinafter. A cleaning device generally designated by 51 and having a cleaning member 51a made of felt or the like is pressed against the roller 41, thereby removing the toner or the like attached to the roller 41. Next the exposure station 33 Will be described in more detail. Referring to FIG. 11 again, a reflecting mirror 52a is disposed at an angle on the right side of and below the original holder device 2 and a tubular light source 53 having a reflector 53a is disposed at the right of a reflecting mirror 52b. The light source 53 emanates the slitlike light so as to illuminate an original to be reproduced which is held stationary upon the original holder 2. The reflecting mirror 52a redirects the light reflected by the original to be reproduced toward a lens 54 having a reflecting mirror 54a integrally formed therewith. The light passed through the lens 54 is condensed and reflected back toward reflecting mirror 52b redirected at an angle and then impinges upon the copy paper 14 passing below the transparent guide plate 34, thereby projecting a moving light image of the original upon the moving copy paper 14. The optical path length between the lens 54 and the original is made equal to that between the lens 54 and the copy paper 1-4. An original holder drive pulley 56 carried by a rotary shaft 55 journalled between the front and rear walls 1a of the main body 1 is disposed below the original holder device 2. A wire or belt 57 is wrapped around the pulley 56 in such a manner that one portion of the wire 57 is fitted into a recess 56a formed in the peripheral surface of the pulley 56 as best shown in FIG. 7 and is held stationary by means of a pin 58 fitted into the recess 56a over the wire 57. After the wire 57 is wrapped over a pulley '59 and a pulley 60, one end 57a of the wire 57 is fixed firmly to the right end 2a; of the frame 2a. The other end 57b of the wire 57 is firmly fixed to the left end 261 of the frame 2a after the wire is Wrappe (1 over the pulley 60. The wire 57 is wrapped over the pulley 60 so as not to interfere with the movement toward either end. The drive pulley 56 will be discussed in more detail hereinafter.

The bent edge of the right frame member 2!; (at the left in FIG. 1) engages with a positioning stopper 61 which is pivotably fixed to the rear wall 1a and whose one arm (lower arm in FIG. 11) is connected to an electromagnetic plunger 62. Therefore, it is seen that the original holder device 2 may be held in stationary position by the stopper 61 from where the photocopying operation is started as shown in FIG. 11. The electromagnetic plunger 62 is energized upon depression of the print-start button 60 whereupon the lower arm of the stopper 61 is pulled toward the plunger 62 so that the engagement between the original holder device 2 and the upper arm of the stopper 61 is released.

In the vicinity of the left side of the frame member 2b of the original holder device 2 is disposed an original positioning member by which the original to be reproduced is held in reproduction position.

The drive mechanism of the photocopying machine of the present invention 'will now be described with reference to FIG. 12. The drive power is supplied from a motor 63 whose drive shaft 63a carries a sprocket wheel 64. The rollers 15, 25, 31, 36, 41, 47 and 49 have sprockets 15a, a, 31a, 36a, 41a, 47a and 49a fixed coaxially thereto respectively. Sprocket wheels 18a and 21a are loosely carried respectively by the pin 18 of the rocking member 16 and the shaft 21 of the cam 19. A sprocket wheel 65 is rotatably fixed to the rear wall 1a above the sprocket wheels 31a and 36a. A sprocket wheel 67 is loosely carried by the shaft 55 of the drive pulley 56 through an electromagnetic clutch (not shown). A reverse sprocket wheel 68 is rotatably fixed at the left of the sprocket wheel 67. A tension sprocket wheel '69 is rotatably fixed to the rear wall 1a at the lower position thereof. An endless chain 71 is wrapped over these sprocket wheels 64, 65, 67, 68, 21a, 18a, 25a, 69, 41a, 47a, 49a, and a sprocket wheel 70 rotatably fixed to the right center position of the rear wall 1a in the order named. The endless chain 71 is advanced in the direction indicated by the arrow 7 in FIG. 12 upon rotation of the motor 63. That is, all of the sprocket wheels except 64 are driven sprocket wheels. The motor 63 is started by depression of the main switch button 6a, as long as the button 6a remains depressed, all of the sprocket wheels are driven thereby transporting the copy paper 14 as described hereinabove.

A sprocket wheel 72 integral with the sprocket wheel 18a is also loosely carried by the pin '18 of the rocking member 16 so that the feed roller 15 may be driven by an endless chain "73 wrapped over the sprocket wheel 72 and a sprocket wheel 15a coaxially fixed to the feed roller 15. The clutch 22 which drives the cam 19 is so arranged as to engage with the sprocket wheel 21a when the start button 60 is depressed.

The sprocket wheels 31a and 36a coaxially fixed to the rollers 31 and 36 are drivingly coupled through a chain 74 to the sprocket wheel 65 so as to be intimately coacted with the sprocket wheel 67 which drives the original holder device drive pulley 56. Thus, the movement of the original holder 2 can be made in precise synchronism with the transportation of the copy paper 14 in the exposure station 33' as described hereinabove.

Next one illustrative embodiment of the time delay control means of the present invention will be described in detail with reference to FIG. 6. This time delay control means is for ensuring the precise optical registration of the leading edges of the original and the copy paper when the latter enters the developing station 38.

As shown in FIG. 6, the drive pulley 56 is loosely carried by the shaft 55 and has two engaging members 56b and 56c which are disposed symmetrical with respect to the axis of the pulley 56. A drive pin 55a extending from the shaft 55 between the members 56b and 560 engages with the member 56b when the shaft 55 rotates in the forward direction indicated by the arrow g, while when the shaft 55 rotates in the reverse direction, the drive pin 55a engages with the member 56c, so that the drive pulley 56 may be rotated in the forward or reverse direction with shaft 55. The member 56b is held in position by means of screws 75 and 76 which are fitted in turn into an arcuate slot formed through the end face of the pulley 56 so that the position of the member 56b may be adjusted by loosening and retightening the screws 75 and 76.

The shaft 55 is drivingly coupled such as through an electromagnetic clutch (FIG. 12) to the sprocket wheel 67 and the sprocket wheel 77 loosely carried by the shaft of the sprocket wheel 68, is drivingly coupled thereto also through an electromagnetic clutch 68a (FIG. 12), and a chain 79 is wrapped over the sprocket 78 carried by the shaft 55 and the sprocket 77. The electromagnetic clutch 90 between the sprocket wheel 67 and the shaft-55 is energized when the switch 29 .(see FIG. 1 1) is closed by the advancing copy paper v14 simultaneously when the chargers 27 and 28 are energized. However, if the pulley 56 was securely fixed to the shaft 55, the pulley 56 would start to drive before the charged copy paper 14 reached the exposure station 33 and the wire 57 would be driven, thereby causing the original carrier 2 to move. As a result the original to be reproduced would be moved not in synchronism with the transportation of the copy paper 14 for exposure. Therefore, in the photocopying machine in accordance with the present invention the time delay control means is provided. More specifically, the pulley 56 is so arranged that it will not start its rotation even when the shaft 55 starts rotation upon closure of the switch 29 and energization of the electromagnetic clutch 90, until the drive pin 55a engages with the member 56b. Consequently, only the charged copy paper 14 arrives at the exposure station 33, will the drive pulley 56 be rotated by the shaft 55, thereby ensuring the synchronization between the movements of the original holder 2 and the copy paper 14 for precise exposure, that is precise registration therebetween.

When the switch 29 is closed, the light source 53 is also energized, even before the leading edge of the copy paper 14 enters into the exposure station 33. This is necessary because it takes generally about 0.5 sec. before the light source can emanate the light at its full luminescence from the time when it is energized. Thus, when the copy paper 14 enters into the exposure station 33, a stabilized light image may be projected thereupon. When the copy paper 14 arrives at the exposure station 33, the drive pulley 56 starts to rotate in the direction indicatedby the arrow e (see FIG. 11) thereby driving the wire '57.'Thus, the original carrierz is caused to move towardthe right in FIG. 11. The velocity of this movement of the original carrier 2 is so determined as to be 'equal to that of the copying paper 14. Upon completion of exposure, the copy paper 14 is admitted into the developing station 38 and the switch 29 is opened in a manner as described hereinabove so that the chargers 27 and 28, the electromagnetic clutch between the sprocket wheel 67 and the shaft 55 and the light source 53 are all de-energized, but the electromagnetic clutch 6811 between the sprockets '68 and 77 is energized. Since this electromagnetic clutch 68a serves to couple to the shaft 55 of the pulley 56 the sprocket 67 which is rotating in the reverse direction as shown in FIG. 12, the rotation of the shaft 55 is reversed. In this case, the drive pin 55a. makes an idle run toward the member 56c and then engages therewith, thereby driving the drive pulley 56 (see'FIG. 6). The time required for the drive pin 55a rotating from the driven pin 56b to the driven pin 560 is a time delay for attaining the precise registration of the leading edges of the copy paper and the original. It should be noted that the driven pin 56b is adjustable in position so that the delay time is also adjustable, whereby the adjustment of the timing relation between the starting of the original carrier 2 and the entrance or admission of the copy paper 14 into the exposure station 38 can be made in a more simplified manner. When the reverse rotation of the drive pulley 56 is stopped, the drive pin 55a remains in engagement with the member or projection 560, so that when the next operation is started, the drive pin 55a. makes a complete idle run from the projection 56c toward the member 56b until the leading edge of the copying paper 14 reaches the exposure station 33.

Upon reverse rotation of the drive pulley 56, the original holder device 2 is returned to the left, that is to its original position. A pin 80 extends from the undersurface of the frame member 2b of the original holder 2 while a rocking lever 81 is pivotably fixed to the rear wall 11a of the main body 1 immediately below the position at which the original holder 2 must be stopped. Therefore, the lever 81 is actuated by the pin 80 when the original holder device 2 reaches the stop position, so that the actuating member 82a of a stop switch 82 is actuated, thereby deactivating the electromagnetic clutch 68a between the sprockets 68 and 77 so as to stop the reverse rotation of of the drive pulley 56.

As shown in FIG. 8, disks 83 and 84 having relatively smooth brake shoes 83a and 8411 made of nylon or the like respectively are so arranged and fixed in position by screws 85 and 86 so as to interpose the flange 56d of the drive pulley 56 between the shoes 83a and 84a. The disk 84 is loosely fitted over pins 88 and 89 extending from a stationary member 87 which in turn is firmly secured to the rear wall 1a. This arrangement serves to apply some brake to the pulley 56 so that the accurate going and returning motion of the original holder device 2 may be ensured. This arrangement serves also to effectively prevent excessive tension from being exerted upon the wire 57 especially when the motion of the original holder device 2 is reversed from the going to returning motion, thereby guarding the drive mechanism safely.

The present invention has been so far described with particular reference to the one preferred illustrative embodiment thereof, but it will be understood that variations and modifications can be effected without departing from the true spirit of the present invention as described hereinabove with reference to the accompanying drawings and as defined in the appended claims.

What is claimed is:

1. In an electrophotographic copying machine of the type wherein an original to be reproduced and a photosensitive copy paper are moved for exposure relative to 10 a slit exposure optical system, the combination comprismg:

(a) means for feeding and transporting copy papers one by one through respective means at a charging station, an exposure station, a developing station and a fixing station;

(b) a carrier for transporting an original in synchronism with the copy paper during exposure at said exposure station; I

(c) carrier drive means including forward clutch means for advancing said carrier, and reverse clutch means for returning said carrier to its initial position after the exposure; and switch means actuated by the passage of the leading edge of a copy paper into said charging station for energizing simultaneously said charging station means, said optical system and said forward clutch means and for deenergizing said charging station means, said optical means and said forward clutch means and energizing said reverse clutch means to return said carrier to its initial position upon the passage of the trailing edge of said copy paper out of said exposure station.

2. An electrophotographic copying machine as in claim 1 wherein said switch means comprises a seesaw switch having two positions and actuated to one position when the leading edge of the copy paper enters into said charging station and to the other position when the trailing edge of the copy paper passes out of the exposing station.

3. An electrophotographic copying machine as in claim 1 wherein said carrier drive means comprises:

(f) a rotary shaft which is coupled to said carrier drive means through said forward and reverse clutch means when said switch means is actuated;

(g) a drive pulley loosely carried on said rotary shaft;

(h) a wire wrapped around said drive pulley a plural number of times and fixed to said drive pulley at a point approximately at the center of the length of said wire wrapped around said drive pulley; and

(i) guide pulley means about which the opposite ends of said wire are passed to be fixed to the leading and trailing edges of said original carrier respectively.

4. An electrophotographic copying machine as in claim 1 including carrier locking means comprising:

(f) an electromagnet;

(g) a hook-shaped member fixed to the leading edge of said carrier; and

(h) a V-shaped lever pivotably fixed to said machine, one arm of which has a notch for engagement with said hook-shaped member when said original carrier is in its initial position and the other arm of which is coupled to said electromagnet, such that upon energization of said electromagnet said V-shaped lever is pivoted releasing said hook-shaped member from said notch.

5. An electrophotographic copying machine as in claim 1 including guide means for said carrier comprismg:

(f) a pair of spaced apart guide rails each having grooves formed in the upper and lower surfaces thereof in the longitudinal direction;

(g) a plurality of ball bearings riding in the grooves in said guide rail;

(h) a channel-shaped retainer member substantially U-shaped in cross section and having spaced apart holes formed through each of the opposing side walls thereof, each of said holes having a diameter substantially equal to that of a ball bearing and a pair of diametrically spaced apart lugs extending radially inwardly and at an angle in opposite directions from its periphery, said retainer member having the upper and lower series of balls rotatably fitted into said holes and prevented from falling out out said holes by said lugs; and

(i) means on said carrier being so fitted over said guide rail that the latter is interposed between said upper and lower series of balls and said carrier slides over said balls when driven.

6. An electrophotographic copying machine as in claim 1 comprising:

(e) means for producing a predetermined time delay between the energizing of said forward clutch means by said switch means and the advancing of said carrier to achieve precise registration of the leading edges of the original and the copy paper upon admission of the copy paper into said exposure station.

7. An electrophotographic copying machine as in claim 6, wherein said time delay means comprises:

(f) a rotary shaft coupled to said carrier drive means for forward and reverse rotation, through said forward and reverse clutch means when said switch means is actuated;

(g) a drive pulley loosely carried on said rotary shaft;

(h) a pair of spaced stop means on one of said rotary shaft and said drive pulley;

(i) a drive pin on the other of said rotary shaft and said drive pulley, arranged for alternate engagement with said spaced stop means to drive said drive pulley respectively in accordance with the forward and reverse rotation of said rotary shaft, said drive pin being normally in engagement with the stop means for reverse rotation of said drive pulley, so that upon rotation of said rotary shaft in the forward direction, there is an idle run before the engagement of said drive pin with the forward rotation stop means whereby a time delay is produced between the initiation of forward rotary shaft rotation and forward drive pulley rotation.

References Cited UNITED STATES PATENTS 3,604,796 9/1971 'Ogawa 355--14 3,424,526 1/1969 Sacre 35510 3,445,160 5/1969 Helland 355-11 3,514,203 5/1970 Zerfahs 355--10 3,493,299 3/ 1970 Hazelton 355-11 SAMUEL S. MATTHEWS, Primary Examiner FRED L. BRAUN, Assistant Examiner U.S. Cl. X.R. 35 5-8 

